1. Technical Field
The present disclosure relates to a phosphor including Sr3MgSi2O8 crystal as the host crystal, and to a light-emitting device having the phosphor. The present disclosure also relates to a projector, a head-up display and a vehicle including the light-emitting device.
2. Description of the Related Art
In recent years, the use of white LEDs has been widespread from the viewpoint of energy saving. A general white LED uses a blue light-emitting element (for example, a blue LED chip) and a phosphor that converts part of the light from the blue LED chip. Specifically, the white LED produces white light by mixing the blue light from the blue LED chip with the light from the phosphor.
A combination of a blue LED chip and a yellow phosphor is the mainstream of white LEDs. To realize higher performances such as color rendering properties and color reproducibility, development is underway on white LEDs that are combinations of a near-ultraviolet to blue-violet LED and three types of phosphors, namely, blue phosphor, green phosphor and red phosphor.
Further, light sources using a combination of a near-ultraviolet to blue-violet laser diode (LD) and a phosphor are under development for use in applications that require high emission energy such as projector light sources and light sources for vehicle headlights.
A phosphor represented by Sr3MgSi2O8:Eu2+ (SMS phosphor) is known as a blue phosphor and is studied for use in white LEDs (see International Publication No. WO 2012/033122).